Jet pack
From Wikipedia, the free encyclopedia
Jet pack, rocket belt, rocket pack, and similar names, are various types of device, usually worn on the back, that use jets of escaping gases to allow the user to fly. The concept of these devices evolved from the 1920s when Buck Rogers, science fiction comic strip hero, used a rocket pack for travel.
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[edit] Types
The first functional model in the world was made in 1958 by Romanian inventor Justin Capra and is exhibited at The Technical Museum Dimitrie Leonida in Bucharest. His invention has never been patented or applied.
In 1960, Bell Rocketbelt was presented to the public. The jet of gas was provided by a hydrogen peroxide powered rocket but the jet can also be provided by a turbojet engine, a ducted fan, or other kinds of rockets powered by solid fuel, liquid fuel or compressed gas (usually nitrogen).
[edit] Hydrogen-peroxide-powered rocket
A hydrogen peroxide-powered motor is based on the decomposition reaction of hydrogen peroxide. Nearly pure (90% in the Bell Rocket Belt) hydrogen peroxide is used. Pure hydrogen peroxide is relatively stable, but in contact with the catalyst (for example, silver) it decomposes into a mixture of superheated steam and oxygen in less than 1/10 millisecond increasing in volume 5000 times: 2 H2O2 = 2 H2O + O2. The reaction is exothermic, i.e. with liberation of much heat (about 2500 kJ/kg), forming in this case a steam-gas mixture at 740 °C. This hot gas is used exclusively as the reaction mass and is directly led to one or more jet nozzles.
The great disadvantage is the limited operating time. The jet of steam and oxygen can provide significant thrust from fairly lightweight rockets, but the jet has a reasonably low exhaust velocity and hence a poor specific impulse. A man's carrying capacity before take-off sets the upper bound on weight of propellant that can be used, and so currently such rocket belts can only fly for about 30 seconds.
A more conventional bipropellant could more than double the specific impulse, however, with peroxide while the exhaust is very hot it is much cooler than other propellants that could be used and this greatly reduces the risk of a fire and injury.
In contrast to, for example, turbojet engines which mainly expel atmospheric air to produce thrust, rocket packs are far simpler to build than devices using turbojets. The classical rocket pack of the construction of Wendell Moore can be prepared in workshop conditions but needs good engineering training and a high level of tool-making craftsmanship.
The main faults of this type of rocket pack are:
- Short duration of flight (to 30 seconds).
- The reasonably high expense of the peroxide propellant.
- The danger of flying below minimum parachute altitude, and hence without any safety equipment.
- The sheer difficulty of manually flying such a device.
These circumstances limit the sphere of the application of rocket packs to very spectacular public demonstration flights (stunts). Rocket pack flights typically seize the attention of spectators and enjoy great success. For example, a flight was arranged in the course of the opening ceremony of the summer Olympic Games 1984 in Los Angeles, USA
[edit] The German Flightpack of World War II
During World War II, Germany made late-war experiments of strapping two wearable shortened Schmidt pulse jet tubes of low thrust to the body of a pilot. The working principle was the same as the Schmidt-Argus pulse jet that powered the Fieseler Fi 103 flying bomb whereas the size was much smaller.
The device was called "Himmelstürmer" (Skystormer) and operated as follows: when the flier ignited both engines simultaneously the tubes began to pulse modulate. The angled rear tube strapped to the flier's back provided both lift and forward thrust while the chest mounted deflector tube of lower thrust maintained a constant upward thrust. This lifted the flier up and forward. By opening the throttle to the rear tube, calculated "jumps" could be made of up to 60 meter (180 ft) at low altitude (under 50 ft, 15 m). The tubes consumed very little fuel but not much could be carried either.
The intended use for this device was for German engineer units to cross minefields, barbed wire obstacles, and bridgeless waters. The device was never intended for troop use, despite a crude depiction of it in that role in the comic book and film The Rocketeer (which was a prop bearing no resemblance to the real device).
At the end of the war this device was handed over to Bell which tested it on a tether out of fear of harm as no test flier was willing to risk his life with the German machine. What became of the device is not known.[1]
The fictional device used by The Rocketeer was a rocket pack that was technically unique (at least in the film adaptation) because it was designed to remain cool. The Himmelstürmer, by comparison, never operated long enough to get extremely hot and both tubes were angled away from the body of the flier. In operation the thrust difference between pulse tubes acted as a push/pull/lift system. Flight time for jumps was in seconds with no lengthy descent time as altitude was minimal. As soon as the throttle was disengaged the device was shut off, a very simple operation and no report of any casualties.[2] [3]
[edit] Turbojets
Packs with the turbojet engine work on the traditional kerosene. They have higher efficiency, greater height and a duration of flight of many minutes, but they are complex in construction and very expensive. Only one working model of this pack was made; it underwent flight tests in the 1960s and at present it no longer flies.
[edit] History
[edit] The Jump Belt (mostly compressed gas powered)
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In 1958 Garry Burdett and Alexander Bohr, engineers of Thiokol Corporation created the "Jump Belt", which they named Project Grasshopper. Thrust was created by high-pressure compressed nitrogen. On the "belt" were fixed two small nozzles, directed vertically downward. The wearer of the "belt" could open a valve, letting out from the nitrogen gas cylinder through the nozzles, in this case it was tossed upward to the height to 7 meters. After leaning forward, it was possible with the aid of the "jump belt"'s thrust to run at 45 to 50 km/h. Then Burdett and Bohr tested a hydrogen peroxide powered version. The "jump belt" was demonstrated by a serviceman in action, but there was no financing, and the matter again did not go to further tests.
The small size of the canisters is likely the reason why the name usage "-belt" rather than "-pack" became customary in the USA.
[edit] Aeropack
In 1959 Aerojet General Corporation won a U.S. Army contract to make a jetpack or rocketpack. At the start of 1960 Richard Peoples made his first tethered flight with his Aeropack.
[edit] Development continues
But American servicemen did not lose interest in this type of flight vehicle. Control of transport studies of the U.S. Army Transportation Research Command, TRECOM) assumed that personal jet apparatuses could find the most diverse uses: for reconnaissance, crossing rivers, amphibious landing, access to steep mountain slopes, overcoming minefields, tactical manoeuvring, etc. The concept was named Small Rocket Lift Device, SRLD.
Within the framework of this concept the administration in 1959 concluded with the company Aerojet General a big contract to research on the possibility of designing an SRLD, suitable for army purposes. Aerojet came to the conclusion that the version with the engine running on hydrogen peroxide was most suitable. However, it soon became known to the military that engineer Wendell Moore of the company Bell Aerosystems had for several years been carrying out experiments to make a personal jet device. After becoming acquainted with his work, servicemen during August 1960 decided to send an order for Bell Aerosystems to develop an SLRD. Wendell Moore was appointed as the chief project engineer.
[edit] Hydrogen peroxide powered rocketpacks
[edit] Bell Textron Rocket Belt
This is the oldest known type of jetpack or rocketpack.
[edit] RB-2000 Rocket Belt
This was a successor to the Bell Rocket Belt.[4] See Bell Rocket Belt#RB2000 Rocket Belt.
[edit] Bell Pogo
The Bell Pogo was a small rocket-powered platform that 2 people could ride on. Its design used features from the Bell Rocket Belt.
[edit] Powerhouse Productions Rocketbelt
More commonly known as "The Rocketman", Powerhouse Productions, owned and operated by Kinnie Gibson, is the first company to manufacture the 30 second flying Rocketbelt[citation needed] and performed Rocketbelt performances exclusively since 1983, including the 1984 Summer Olympics, Carnival in Rio de Janerio, Super Bowls, the Rose Parade and Daytona 500, Michael Jackson. Powerhouse Rocketbelt pilots include Kinnie Gibson, Eric Scott and Dan Schlund.[5]
[edit] Tecnologia Aeroespacial Mexicana (TAM)
The Tecaeromex Rocket Belt is or was made by Tecnologia Aeroespacial Mexicana, which is said to be made by the only company in the world that offers a flying and tested rocket belt package, featured in the March 2006 issue of Popular Science magazine and many TV programs around the world like the Discovery Channel, the BBC, ProSieben, TV Azteca, The Science Channel, The History Channel. Its maker claims that four of his rocketpacks are flying now; his first tethered flights were on 22 September 2005.
On Aug. 11, 2006 Isabel Lozano was the first woman in the world to fly tethered in a rocket belt in front of millions of TV spectators; she flew with a special rocket belt built by TAM. [1]
[edit] Turbojet pack (Bell Jet Flying Belt)
In 1965 Bell Aerosystems concluded a new contract with the Defense Advanced Research Projects Agency (DARPA) to develop a jet pack with a turbojet engine. This project was called the "Jet Flying Belt", or simply the "Jet Belt". Wendell Moore and John K. Hulbert, a specialist in gas turbines, worked to design a new turbojet pack. Williams Research Corporation (now Williams International) in Walled Lake, Michigan, designed and built a new turbojet engine to Bell's specifications in 1969. It was called the WR19, with a rated thrust of 195 kgf (1,910 newtons) and weighing 31 kg.
The first free flight of the "Jet Belt" took place on 7 April 1969 at the Niagara Falls Municipal Airport. Pilot Robert Courter flew about 100 meters in a circle at an altitude of 7 meters, reaching a speed of 45 km/h. The following flights were longer, up to 5 minutes. Theoretically, this new pack could fly for 25 minutes and go up to 135 km/h.
In spite of successful tests, the U.S. Army lost interest. The pack was complex to maintain and too heavy. Landing with its weight on his back was hazardous to the pilot, and catastrophic loss of a turbine blade could have been lethal.
Thus, the "Bell Jet Flying Belt" remained an experimental model. On 29 May 1969, Wendell Moore died of complications from a heart attack he had suffered six months earlier, and work on the turbojet pack was ended. Bell sold the sole version of the "Bell pack", together with the patents and the technical documentation, to Williams Research Corporation. This pack is now in the Williams International company museum.
[edit] Special features of the turbojet pack
The "Jet Belt" used a small turbofan engine, which was mounted vertically, with its air intake downward (1). Intake air was divided into two flows. One flow went into the combustion chamber, the other flow bypassed the engine, then mixed with the hot turbine gases, cooling them and protecting the pilot from the high temperature. In the upper part of the engine the exhaust was divided and entered two pipes, which led to jet nozzles (2). The construction of the nozzles made it possible to move the jet to any side. Kerosene fuel was in tanks (33) beside the engine. Control of the turbojet pack was similar the rocket pack, but the pilot could not tilt the entire engine. Maneuvering was by deflecting the controlled nozzles. By inclining levers, the pilot could move the jets of both nozzles forward, back, or sideways. The pilot rotated left/right by the turning the left handle. The right handle governed the engine thrust. The jet engine was started with the aid of a powder cartridge. While testing this starter, a mobile starter on a special cart was used. There were instruments to control the power of the engine, and a portable radio to connect and transmit telemetry data to ground-based engineers. On top of the pack was a standard auxiliary landing parachute (4); it was effective only when opened higher than 20 meters.
[edit] In space
Rocket packs can be useful in outer space, where much less thrust is needed, because the weightlessness of space removes the need to continually fight against gravity.
Rocket packs were tested during mission STS-64. Mission Specialists Carl Meade and Mark Lee tested the SAFER Rocket Pack while Hammond remained inside the Orbiter.
[edit] NASA's Manned Maneuvering Unit (MMU) (compressed gas powered)
In the 1980s, NASA demonstrated the Manned Maneuvering Unit (MMU), a rocket pack that allowed an astronaut to function as his/her own spacecraft, but the system was retired before the decade was gone. The MMU is the only jetpack of practical importance. Its operational area is outside a space station or spacecraft, where an astronaut can limitedly move independently. The MMU's propulsion was produced by high-pressure nitrogen gas discharged through nozzles (which the MMU has 24 of). The MMU was used since 1984 in three Space Shuttle missions (STS-41-B, STS-41-C and STS-51-A).
[edit] NASA's SAFER
Recently, NASA has introduced the SAFER, a smaller simpler version of the MMU meant to be used in case of accidental separation from spacecraft or station. With only small amounts of thrust needed, safety and temperature are much more manageable than in Earth gravity in the atmosphere.
[edit] Jet pack or rocket pack with wings
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Jetpacks and rocketpacks would likely have much better flight time on a tankful of fuel if they had wings. There have been occasional real cases of a man gliding horizontally long distances with his body horizontal and no flying aid except a pair of rigid airplane-type wings strapped directly to his body; see also wingsuits.
[edit] Visa Parviainen's jet-assisted wingsuit
On 25 October 2005 in Lahti in Finland, Visa Parviainen jumped from a hot air balloon in a wingsuit with two small turbojet jet engines attached to his feet. The turbojets provided approximately 16 kgf (160 N, 35 lbf) of thrust each and ran on kerosene (JET A-1) fuel. Visa apparently achieved approximately 30 seconds of horizontal flight with no noticeable loss of altitude.[6]
[edit] Yves Rossy's jetpack
A Swiss former military pilot Yves Rossy developed and built a winged pack with aerodynamic rigid aeroplane-type carbon-fiber wings with a span of about 8 feet, and four small kerosene-burning jet engines (developed by the German Jet-Cat company) under the wings; these engines are a large version of a type designed for model aeroplanes. He can achieve true flight with it. He uses his body and a hand throttle to manoeuvre. Rossy says he has become "the first person to gain altitude and maintain a stable horizontal flight thanks to aerodynamic carbon foldable wings". The wings can fold and unfold (by one hinge at the midpoint of each wing) while flying.
His first successful trial was on 24 June 2004, near Geneva, Switzerland. Yves Rossi has made more than 30 motorized flights since then. After being lifted by a Pilatus Porter plane, he jumps out of it with his wings folded, unfolds them as he falls, and flies horizontally for up to 6 minutes and 30 seconds, then lands using a parachute. [2]
It was exhibited on 18 April 2008 at the opening day of the 35th Exhibition of Inventions at Geneva. [3]
He wears a heat-resistant suit like a firefighter's or racing driver's, to protect him from the hot jet blast. [4]
- Links to images
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- On the ground
- Wings folded
- Wings folded, front view
- Wings unfolded, front view
- Close-up view of underside with jetmotors and harness, wings unfolded
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- Flying
[edit] Current technology
According to the USA Government, real jetpacks have little practical value due to the limitations of current technology. The United States military, which conducted most jet pack research, has declared that helicopters are far more practical. Many others have worked on devising a functional jet pack, but with limited success.
In recent years the rocket pack has become popular among enthusiasts, and some have built one for themselves. The pack's basic construction is rather simple, but its flying capability depends on two key parts: the gas generator, and the thrust control valve. The rocket packs being built today are largely based on the research and inventions of Wendell Moore at Bell Aerospace.
One of the largest stumbling blocks that would-be rocket pack builders have faced is the difficulty of obtaining concentrated hydrogen peroxide, which is no longer produced by very many chemical companies. The companies who produce high concentration hydrogen peroxide only sell to large corporations or governments, forcing some amateurs and professionals to make their own hydrogen peroxide distillation installations. Since 2005, more rocket packs are being built and tested out, since hydrogen peroxide has become more readily available. [5]
Two high-profile jet pack projects are currently being operated by Jet pack International and Tecnologia Aeroespacial Mexicana (TAM).[6] Jetpack International's Jet Pack H202 was flown for thirty-four seconds in Central Park on the 9 April 2007 episode of the Today Show, and retails for $150,000. TAM sells its custom-built TAM Rocket Belt for $250,000.
[edit] In popular culture
Jet packs or rocket packs have been used in some films, such as the 1965 James Bond film Thunderball and the 1991 Disney film The Rocketeer, and have long been a staple of science fiction in comic books and novels. On Michael Jackson's "Dangerous Tour," a stunt double flew a rocket jet at the end of his concerts. In the 1960s the "Bell Rocket Belt" was on the peak of popularity. Bell arranged demonstration flights in the U.S. and other countries, each time causing the public enthusiasm.
In the filming of Thunderball, two packs were used. One was a non-functional prop: it can be seen on Sean Connery in the large-scale planning scenes. The second was a genuine Bell Rocket Belt and it actually flew, piloted by Bell Company pilots Bill Suitor and Gordon Yaeger. The scenes with Sean Connery and the pack had to be shot twice, because the first time they photographed it his head was uncovered, and in the flying shots Bill Suitor flatly refused to take off without a crash helmet.
In the film's sound track the real shrill roar of the rocket pack's engine was replaced with the hiss of a fire extinguisher "to seem more realistic".
In Fahrenheit 451 (1966 film), a jet-pack-equipped search squad is hunting the main protagonist.
In the 2002 film Minority Report, the pre-crime cops routinely use jet-packs.
In the Comic book, and 2008 film, Iron Man, the hero uses a jet-pack that is built into his armour.
A rocket pack occurred famously on the opening of the summer Olympic Games in Los Angeles in 1984. The pack was piloted by both Bill Suitor and Gordon Yaeger. Suitor was a legendary personality (in all calculation more than 1200 flights — more than in any other pilot to this day). Bill took off from platforms, flew above many spectators, who from the unexpected contingency covered their heads with their hands, and landed opposite the presidential platform, where Ronald Reagan sat. This flight was seen by 100,000 spectators on the platforms and about 2.5 billion television viewers.
In the Star Wars films, games, and literature, many characters, including Boba Fett and Jango Fett, use jetpacks or rocketpacks.
In the G.I. Joe: A Real American Hero toyline, a toy called Jet Mobile Propulsion Unit (JUMP) was part of the original 1982 release. In was repackaged in 1983 with Grand Slam.
In the popular online game Club Penguin, in one of the games the player flies a jetpack.
During the Buffy the Vampire Slayer episode "Seeing Red", Warren Mears escapes from Buffy using a jetpack; Andrew Wells reveals he too has a jetpack, but when he tries to escape, he only knocks himself out on the overhanging roof above him.
In Disney's Kim Possible, Kim Possible and her partner Ron Stoppable use winged jetpacks which are hidden in backpacks before use.
The jetpack also appears in computer games like Starsiege: Tribes, Grand Theft Auto: San Andreas and in Command & Conquer: Tiberian Sun, where Global Defense Initiative has infantry which are equipped with jetpacks.
The Jetpack is also a device used in some of the Worms games.
[edit] Making a rocket pack at home using plans from the Internet
As depicted in Episode 32 of MythBusters, according to an urban legend, a jetpack or rocketpack may be affordably built from plans purchased off the Internet (Extensive modification was made to the plans by the MythBusters due to the plans' vague nature, and also due to the infeasible engine mounting system that they specified). The jetpack produced by the MythBusters, where two ducted fans were powered by an unnamed ultralight type engine was not powerful enough to lift a person off the ground, and was expensive to build. The plans specified a Rotax 503 ultralight engine but they were going to use the more powerful and lighter Rotax 583 engine until a similar type but lighter unnamed engine was substituted[7].
Even if an operational rocket pack could be built, as is the case with the Rocketpack recently constructed by the USA's only "private rocketeer" Gerard Martowlis; flying a pack is both extraordinarily difficult and extremely dangerous. Like all previous Rocket Belt pilots his recent tests of the belt are performed with the use of a Safety Tether System to prevent injury due to loss of control. It takes many, many hours of practice to learn to fly the pack and this training carries a high cost in propellant. Even when trained, the low flight time of any peroxide-based pack means that the entire flight is below the minimum parachute altitude so any loss of control or failure of the pack is highly likely to be fatal.
[edit] See also
[edit] References
- ^ Himmelsturmer
- ^ Unreal Aircraft - Q Branch - German Rocket Pack - WW2
- ^ "German Secret Weapons and Wonder Weapons of World War II", Christof Friedrich, Samisdat Publications, 1976
- ^ RB 2000
- ^ The Rocketman
- ^ BIRDMAN, Inc. / Oy
- ^ http://kwc.org/mythbusters/2005/06/mythbusters_jetpack_pyramid_po.html
10. http://www.rocketbelts.americanrocketman.com/martowlis.html
[edit] External links
- The Rocketman The company performing Rocketbelt flights worldwide.
- Rocket Belt. Peter Guisbert's site, dedicated to the history of rocket pack. Enormous quantity of information and photographs.
- U.S. Army Transportation Museum about rocketpacks including the "Bell Rocket Belt".
- Web-site with video
- Flying into the Future: Ky Michaelson's Jet pack site
- Popular Mechanics comparison of the TAM Rocket Belt and Jetpack International's Jet Pack H202
